The speed of sound at room temperature on a dry day is 768 miles per hour or a little over 1000 feet per second. That may sound fast, but as we all have experienced during a thunder storm, it's a measurable delay.

What does this have to do with business telephone systems?

In many cases it's important to have a public address or paging system as part of the business phone system. Car dealers, manufacturing facilities, medical centers, and retail operations (to name several) have a need to alert people who could be anywhere in the facility. This is done by installing an overhead paging system.

This is where the speed of sound is relevant. I have seen (or rather heard) many systems where the paging speakers are installed at opposite corners of a facility facing toward the center. Although this seems logical, it's the wrong way to position the speakers and makes the pages hard to understand. Here's why...

If you are standing in the direct center of a facility and the paging speakers are equal distance from you, the sound takes the same amount of time to reach you from each paging speaker, and the audio will be clear. But, if you are closer to one speaker than the other, the sound from the closer one raches you before the one that's farther away. The sound that you hear is muddled because of the delay between the two sources.

The correct way to arrange the speakers is to create a "wave of sound". Speakers need to all face the same direction. Usually the speakers are arranged in rows, equally spaced and angled downward at 45 degrees, with rows starting at the back wall. I have a slide rule that calculates how many speakers are required based on the room dimensions and ambient noise level. For example, in a 50,000 square ft warehouse, with moderate noise, eight horns would be appropriate.

If the paging system in your facility is not easy to understand, or you think having a public address system would benefit your business, contact me. It may be as simple as moving some of the speakers to the right location.

Update for 2017 - Thank you for visiting and reading my post. This has been a popular post so I have updated the information to include paging for cloud or hosted phone systems. Follow this link to read the upated post: